The use of slack limiters in cassette tapes, particularly video cassette tapes, is well known. Slack limiters are necessary since excessive looseness or slackness in the run of magnetic tape within the cassette causes the magnetic tape to deviate from a substantially straight path between the tape guides provided at opposite ends of the cassette housing. Thus, excessive looseness or slackness in the magnetic tape run causes the magnetic tape not to be properly engaged by the magnetic head or by the tape engaging member of the tape loading device. Such improper engagement may lead to damage of the magnetic tape, or to defective recording or reproducing functions, and may also contribute to damage or deterioration of the tape during storage or non-use of the tape cassette.
Various solutions have been promogated to alleviate the problem of excessive tape slackness within a tape cassette. One of these known solutions involves the provision of resiliently flexible elements, or pressure flaps, secured within the cassette housing in contact with the tape run. The pressure flaps are deflected in response to tension in the engaged tape portion to provide progressively increased resistance to movement of the magnetic tape that deviates from a substantially straight path between the tape guides.
Currently known pressure flaps usually include a generally planar body portion having a tape engaging edge at one end, with a securing arrangement at an opposite end. Configurations of the securing arrangements have included using adhesives to glue the pressure flap into place, arrangements in which the pressure flap is secured to a post within the cassette housing, and various arrangements in which a flap or folded portion is received within a recess in the cassette housing. Pressure flaps utilizing the latter approach employ a generally planar tab or folded portion extending at an angle from the planar body portion of the pressure flap. During assembly of the cassette, the tab or folded portion of the pressure flap is inserted into a correspondingly-shaped recess provided in one half of the cassette housing.
Known pressure flaps have exhibited several disadvantages. The flat configuration of the body portion, in conjunction with the relatively small side of the pressure flap, results in making single piece handling during production of the pressure flaps, and during assembly of the cassette housing, relatively difficult. Since both sides of the flat body portion are identical, there is no means by which the pressure flap may be positively oriented for assembly and insertion into the cassette, other than by visual inspection. Furthermore, the flat configuration necessitates that the strength and resiliency of the pressure flap is largely dependent upon the material from which the flap is fabricated.